Cervical Presentation of Thymic Cysts Alexander M. Guba, Jr, MD, MAJ MC, Washington, DC Andrew E. Adam, MBBS, Sqn Ldr RAF, Washington, DC Darrell A. Jaques, MD, Baltimore, Maryland Robert G. Chambers, MD, Baltimore, Maryland
Embryologically, the thymus gland originates from the third branchial pouch bilaterally at the sixth week of development, as illustrated in Figure 1. During the subsequent three weeks these hollow pouches become cellular and descend into the mediastinum. Rests of thymic tissue commonly persist in the neck along the route of descent of the gland into the anterior mediastinum. Indeed, three varieties of thymic tissue located in the neck have been described in the literature. Among these, aberrant solid thymic rests are commonly found at autopsy and are usually of little clinical importance. Wenglowski [I] in 1912 demonstrated cervical thymic tissue in twenty-three of seventy-five patients at autopsy. Gilmour [2] in 1941 found thymic tissue in the neck of thirteen patients at autopsy. Such tissue may be confused with metastatic squamous cell carcinoma during frozen section examination at parathyroid exploration. The second type of thymic tissue encountered is cervical thymoma. These tumors have been found at both autopsy and operation for cervical mass [3-71. Finally, cystic thymic tissue is the most important of the three types of cervical thymus because of its clinical presentation. Cystic thymic tissue was first excised from a patient presenting with a neck mass in 1901 by Pollosson and Piery [8]. During the subsequent seventy-six years,
From the Division of Surgery*, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, DC, and the Uniformed Services University of the Health Sciences, Bethesda, Maryland. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. Reprint requests should be addressed to Alexander M. Guba, Jr, MD. Division of Surgery, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, DC 20012. Presented at the Joint Meeting of the American Society for Head and Neck Surgery and the Society of Head and Neck Surgeons, Toronto, Ontario, Canada, May 29-31, 1978.
430
fifty-five additional cases of cervical thymic cyst have been reported in thirty-nine publications [2,9-461. These fifty-six cases, with sixteen previously unreported cases of cervical thymic cyst, form the basis of the present report. Material and Methods Cases were obtained from the authors’ practices and the records of the Armed Forces Institute of Pathology (AFIP), Washington, DC. The patients’ records and pathology reports were reviewed, and hematoxylin and eosin preparations were examined by us. Results
Literature Review. Fifty-six cases have been presented in the literature with histologic confirmation of cervical thymic cyst. (Many of the references did not provide complete data concerning the patients presented. Percentages given are compiled from the available information.) The average age was twelve years, although the median age at presentation was seven years. Seventy per cent were male. Seventy per cent of the patients had left-sided neck masses, 23 per cent had right-sided neck masses, and the remainder had midline or pharyngeal masses. The cervical mass was noted to be present an average of 9.8 months prior to surgery, whereas the median time interval from onset to operation was three months. Ninety per cent of patients complained of painless swelling, 3 per cent noted a posttraumatic mass, and 6 per cent presented with dyspnea, hoarseness, and dysphagia. Present Study. Sixteen patients undergoing surgical exploration for a neck mass were found to have cervical thymic cysts. Two were treated at the Greater Baltimore Medical Center, one was treated at Walter Reed Army General Hospital, Washington,
The American
Journal of Surgery
Cervical
Presentation
of Thymic
Cysts
TONSIL HYPOBRANCHIAL
EMINENCE&
Ill-
INFERIOR
PARATHYROID
LARYNGOTRACHEALGROOVE
THYMUS
FOURTH
AND
FIFTH
RIOR
DUCT OF POUCHES YROID
Figure 1. Embryonic pouches.
remainder were asymptomatic. Six had right-sided neck masses, seven had left-sided masses, and three had midline neck masses. Ten of the sixteen masses were either within the anterior triangle of the neck or lying under the lateral border of the sternocleidomastoid muscle. Common preoperative diagnoses were branchial cleft cyst, cystic hygroma, lymph node, thyroid nodule, and thymus. Pathology. The principal gross and histologic findings are outlined in Table II. Intraoperatively, cervical thymic cysts were found to be variable in size,
Clinic&l Data Age WY
Case
GLAND
pharyngeal
DC, and two were treated at Fitzsimons Army Medical Center, Denver, Colorado. The charts and histologic sections of the tumors from the remaining patients were located at the Armed Forces Institute of Pathology, Washington, DC. Pertinent clinical data are shown in Table I. The average age of patients was 18.8 years. Seven males and nine females were included. The cervical mass had been present an average of 4.5 months prior to operation. Four patients had some degree of pain associated with the mass, one had dysphagia, and the TABLE I
PARATHYROID
Sex
Duration of Mass
Symptoms
1 2
7/M 25/F
5.5 mo 2mo
None Sore throat
3 4
15/M 14/M
1.5 mo 3 mo
Pain Dysphagia
5 6 7
36/F 35/F 26/M
3mo 4mo 16da
Tender 3 days Cough None
a
7/F
2 yr
None
9
30/F
Unknown
Thyrotoxicosis
10
4/M
Unknown
11 12 13
24/M 4/F 10/F
5 wk 5 da 7 mo
Pain None None
Right neck Medial border right sternocleidomastoid muscle Left neck Left anterior triangle Left neck Suprasternal notch Left anterior triangle Left anterior triangle Right suprasternal notch Right anterior triangle Left neck Right neck Right neck
14 15 16
22/F
3mo
None None None
Suprasternal notch Left neck Suprasternal notch
ah4 32/F
Volume 136, October 1976
1 yr 1 wk
Preoperative Diagnosis
Location
Branchial cleft cyst: cystic hygroma Branchial cleft cyst
Left neck mass Left neck cyst Branchial cleft cyst Unknown Unknown Cystic hygroma Toxic goiter Branchial cleft cyst Lymph node Thyroid nodule Branchial cleft cyst; cystic hygroma; thymus Anterior neck mass Cystic hygroma Thyroid cyst
431
Guba et al
TABLE II
Patholoaic Data Mediastinal Connection
Cyst Size (cm)
Case
I5 x 2.5 4X3X 1.5 4X 1.8 x 1.2 2x2 2.5 X 1.5 3X4X 2.5 7.5 x 4 x 3.5 5X4X 3.5
Contents of cyst Turbid gray-brown
CuboidaVsquamous
+
++
Turbid
+
+
Duct extending 12 cm inferiorly None Inferior fibrous tract None
Friable yellow-brown
Flattened cuboidab squamous Flat squamoid
++
+
Gelatinous Solid/cystic Serous
Stratified squamous Flattened cuboidat Low cuboidal
++ +
+ +
Cystic tail
Straw cofored
SquamousIcuboidal
+
++
Nipple-like projection 3 cm cystic None
Green-brown gelatinous
No lining
-
-
Unknown
None
Yellow fluid with hemorrhage Dry cheesy
Pseudostratified ciliated columnar Simple/stratified squamous Flat cuboidal
0.1 x 0.9
10
4.5 x 3 Xl 3.5 x 2.9 x 1.4 3x 1.5 x 1.5
None
None
Yellow-orange
14 x 3.5
Projection from mediastinum None Extension into mediastinum
Gray-white
Substernal pedicle
Unknown
12 13 14 15
1.5 15 x 4.5
16
1.5 x 2
Hassall’s Corpuscular Degeneration
Solid core into mediastinum None
9
11
Lining
Cholesterol Granuloma or Clefts
Unknown Unknown
soft, and usually lobulated. They were frequently elongated, possessing a cephalad or caudal extension, as shown in Figure 2. The wall of the major cyst space varied in thickness from a few millimeters to as much as 1 cm. Cyst contents varied from clear fluid to turbid, semi-solid material. Roth the external capsule and internal septae of the cysts were composed of highly cellular and vascularized fibrous tissue. Lymphocytes were present in aggregates and in a diffuse, scattered pattern, with both Hassall’s corpuscles and strands and nests of thymic epithelial elements found among them, as shown in Figures 3 and 4. Thymic cellular elements were in intimate relation to the cyst lining. Cholesterol type granulomata were present in eleven of sixteen patients. (Figure 5.) There was wide variation in the type of lining epithelium, as shown in Figure 6. Comments
From the clinical findings reported by others and from our own study involving sixteen patients, it can be seen that 75 per cent of patients with histologically
It
++
++
+
-
Flat cuboidal
++
-
Simple squamous
++
+
+
++
-
+
No lining Stratified squamous, flat granulation tissue Low cuboidal
proven cervical thymic cyst were less than twenty years old at presentation. Overall, cervical thymic cysts were found more frequently in males, even though a slight female predominance was noted in our study. More than 80 per cent of the patients complained of a slowly enlarging, painless mass. The remainder presented with dysphagia, hoarseness, and dyspnea. Occasionally, a cervical thymic cyst became suddenly evident or abruptly painful after an initially painless course, as in cases 3 and 5. Fluctuation in size, presumably due to infection or hemorrhage, was noted in cases 4 and 13. Symptoms were usually present for several months prior to consideration for operation. All cervical thymic cysts were said to be mobile at the time of physical examination. Concomitant diseases were present in two of our sixteen patients. One patient (case 11) initially presented with a left-sided tender mass that proved to be a cervical thymic cyst. Six months later, he presented with a second left-sided mass. This proved to be intranodal Hodgkin’s disease. Review of the sections of the initial specimen failed to show any diagnostic features of Hodgkin’s disease. Cervical
The American Journal of Surgery
Cervical Presentation of l’hymic Cysts
thymic cyst was a chance finding in a thirty year old female (case 9) operated on for thyrotoxicosis. The preoperative differential diagnoses included lymph node, branchial cleft cyst, cystic hygroma, and thyroglossal duct cyst. From the literature it seems that a firm diagnosis of cervical thymic cyst has not been made preoperatively. Case 13 from our series may represent a correct preoperative diagnosis. This ten year old female presented with a rapidly growing and very long lateral neck mass that proved to extend from the mandible to the mediastinum and measured 14 by 3.5 cm. A preoperative chest x-ray film revealed widening of the superior mediastinum and tracheal deviation to the left. It drew the written comment fl-om one clinician: “I think this is thymus.” It has been stated that as many as 50 per cent of cervical thymic cysts may be continuous with mediastinal thymus. This may be by direct extension of t:ne cyst substernally or by connection to a solid cord or vestigial remnant of thymic tissue which extends into the thorax. Such a connection was present in eight of our sixteen patients. Cervical thymic cyst has rarely required extensive operative time or dissection. F’rozen section diagnosis of cervical thymic cyst should help the surgeon determine the extent of the procedure necessary for removal of the tumor. Histologically, the presence of thymic epithelial elements in intimate relation to the cyst lining is essential to the diagnosis of cervical thymic cyst. Has~11’s corpuscles or diffuse thymic epithelial elements should be evident; otherwise the tissue cannot be histologically distinguished from tissue of a branchial cleft cyst. Cholesterol type granulomata or clefting is usually present. There is no uniformity regarding the composition of cyst lining in cervical thymic cyst. As in mediastinal thymic cysts, the lining may be nonexistent or it may be composed of cuboidal, ciliated columnar, simple squamous, or stratified squamous epithelium with variable amounts of inflammatory cellular infiltrate, granulomatous tissue, and fat-laden histiocytes. The origin of cervical thymic cyst has been debated in the literature. Speer [47] discussed five possible origins of cervical thymic cysts: (1) embryonic remnants; (2) sequestration of involuted areas; (3) degenerating Hassall’s corpuscles; (4) blood or lymph vessels; and (5) neoplastic processes. More recently, authors [27,44] have condensed these to two: (1) degeneration of Hassall’s corpuscles and (2) a congenital origin with tissue arising from the thymopharyngeal duct. All but five of our patients showed degeneration of Hassall’s corpuscles; the spectrum of degeneration extended from focal or partial degene:*ation of a corpuscle to the formation of a microcyst
Volume
136,
October
1976
Figure 2. Case 4. Operative photograph of thymic cyst.
with a flattened epithelial lining identical to that of the main cyst cavity and surrounding granulomatous reaction. The granulomatous reaction to which we have already referred is consistent with a reaction to cholesterol and has repeatedly been described as such in the literature. To our knowledge, this has not been established histochemically. Moreover, although some authors suggest that it is caused by the breakdown products of hemorrhage, the evidence for intracyst bleeding (as hemosiderin pigment 1is scanty
433
Guba et al
Figure 3. Case 4. Microcysts developing within thymfc cyst wall. Note cholesterol type cleftfng within the lumen. (Magnfffcatton X40; reduced 53 per cent. )
Figure 4. Case 15. Photomfcrograph of degenerating HassaIl’s corpuscle in cervical thymic cyst. Note development of epithelial lining similar to that of cyst cavity. (Magnification X lOti; reduced 53 per cent. )
in our series. We prefer to regard this as a foreign body reaction secondary to a product of epithelial cell degeneration, such as keratin. An observation favoring the congenital origin of cervical thymic cyst is the relatively frequent association of cervical thymic cyst with other endocrine gland inclusions. Five of our sixteen patients had fragments of other endocrine tissue. In cases 12 and
434
15, discrete nests of normal parathyroid tissue were seen at a distance from the cyst lumen and were considered inclusions. Similarly, in case 7 a cyst in the left anterior cervical triangle had an inferior prolongation reaching into the superior mediastinum. Although the cyst was clearly of thymic origin, the tail contained normal thyroid tissue in close approximation to thymic elements.
The American Journal of Surgery
Cervical Presentation of lhymic
Figure 5. Case 3. cholesterol type mata in cervical nification X40; cent. )
Cysts
Photomicrograph of clefts and granufothymic cyst. (Magreduced 53 per
Figure 6. Case 15. Photomicrograph ikstrating variety of lining epithefium within a single specimen: simple cuboidal; flattened; and focally pseudostratified epithelium. ( Magnification X40; reduced 53 per cent. )
Two additicmal cases from AFIP files not included wit,h the sixteen reported herein were reviewed. It was not possible to be certain whether the appropriate diagnoses were parathyroid cyst with aberrant thymic tissue or vice versa. Considering the complicated descent of the thymic primordia and their common origin from the third branchial pouch with the parathyroid III glands, such close association
Volume
136.
October
1976
between thymic and parathyroid tissue is not surprising. Thus, elements of both the congenital and degenerative theories have to be employed to adequately explain the development of cervical thymic cysts. Finally, it should be recognized that cervical thymic cyst belongs in the differential diagnostic list of neck masses, particularly in children and occasionally in adults.
435
Guba et al
Summary
Sixteen cases of cervical thymic cyst are added to the previously reported fifty-six cases. Seventy-five per cent of the patients were less than twenty years old. Eighty per cent complained of a painless mass preoperatively. The histologic diagnosis of cervical thymic cyst was made if thymic epithelial elements could be found adjacent to the cyst cavity; Hassall’s corpuscles were usually present. Cholesterol granulomata could usually be identified. The theories of origin of cervical thymic cyst are discussed. Acknowledgments: We would like to acknowledge John White, MD, BG MC and Robert Muir, MD, COL MC for their contribution of two patients to this series.
References 1. Wenglowski R: Ueber die Halsfistein und Cysten. Arch K/in Chir 100: 789, 1912-1913. 2. Gilmour JR: Some developmental abnormalities of the thymus and parathyroids. J Path01 Bacterial 52: 213, 1941. 3. Wadon A: Thymoma intratracheale. Zenfralbl A//g P&ho/ 60: 308, 1934. 4. Boman K: Om thymusfoeraendringar vid myasternier. Nerd Med 10: 1625, 1941. 5. Pirkey WP: Epithelioma of undescended thumus in a child. Arch Otolaryngol59: 237, 1954. 6. Sease Cl: Cervical thymoma: a case report. V Med 83: 345, 1956. 7. Ridenhour CE, Henzel JH, DeWeese MS, Kerr SE: Thymoma arising from undescended cervical thymus. Surgery 67: 614, 1970. 8. Pollosson A, Pi&y M: Un eas d%pittiliome primitif due thymus. Providence Med 15: 1, 1901. 9. Pezcoller A: Contribute allo studio delle cisti congenite del cello di origine timica. C/in Chir 32: 272, 1929. 10. Fielding JF, Farmer AW, Lindsay WK, Conen PE: Cystic degeneration in persistent cervical thymus; a report of four cases in children. Can J Surg 6: 178, 1963. 11. Hyde TL, Sellers ED, Owen M: Thymic cyst of the neck. Tex Med 39: 539, 1944. 12. King ESJ: The lateral lympho-epithelial cyst of the neck. Aust NZJ surg 19: 109, 1949. 13. Heinz ID: The association of lymphoid and epithelial tissue in the neck and mediastinum, ~69. Studies in Pathology Presented to Peter MacCallum. Victoria, Australia, Melbourne University Press, 1950. 14. Arnheim EF, Gemson BL: Persistent cervical thymus gland: thymectomy. Surgery 27: 603, 1950. 15. Weller RW, Pearce AE, Rapoport M: Thymic cyst of the neck. Arch Pathol52: 569, 1951. 16. Moseley JE, Som M: Cervical thymus gland. J Mf Sinai Hasp 21: 289, 1954.
436
17. Sorensen HR, Jorgensen JB, Thomsen G, Westergard-Nielsen V, Eskelund V: Thymogenic tumours and cysts. Acta Chir Stand 110: 353, 1956. 18. Williams RR, Gerber DM: Aberrant cystic thymus gland of the neck. Am J Surg 93: 473, 1957. 19. Crawford AS, Evans PV, Thompson W: Thymic cyst in the neck; case report. J Indiana State MedAssoc 50(6): 715, 1957. 20. Willis RA: The Borderland of Embryology and Pathology. London, Butterworth, 1958, p 281. 21. Viar WN, Donald JM, Clemmons LH: Thymic cyst in the neck. Am Surg 25: 18, 1959. 22. Lane D: Thymic cyst. Med JAust 47: 419, 1960. 23. Cote R, For-tin C: Thymic cysts of the neck. Can J Surg 4: 566, 1961. 24. Ozlu C, Allen JD: Unilateral thymic cyst of the neck. J Ky Med Assoc 60: 743, 1962. 25. Lewis MR: Persistence of the thymus in the cervical area. J Pediatr61: 887, 1962. 26. Gaeckle DJ, Gerber ML: Thymic cyst in the neck. Am J Surg 103: 755, 1962. 27. Behring C, Bergman F: Thymic cyst of the neck. Acta Pathol Microbial Stand 59: 45, 1963. 28. Simons JN, Robinson DW, Masters FW: Cervical thymic cyst. Am J Surg 108: 578, 1964. 29. Keen JA: A case of persistent thymus diverticula in the neck. S Af[ J Lab C/in Med 10: 48, 1964. 30. Bieger RC, McAdams AJ: Thymic cysts. Arch fathol82: 535, 1966. 31. lndeglia RA, Shea MA, Grage TB: Congenital cysts of the thymus gland. Arch Surg 94: 149, 1967. 32. Ellis HA: Cervical thymic cysts. Br J Surg 54: 17, 1967. 33. Dabby V: Cervical thymic cyst. J F/a Med Assoc 56: 852, 1969. 34. Barrick B, O’Kell RT: Thymic cysts and remnant cervical thymus. J Pediatr Surg 4: 355. 1969. 35. Hinds EA. Linkner LM, Cloud DT, Trump DS: Ectopic thymic tissue of the neck. J Pediatr Surg 5: 460, 1970. 36. Ratnesar P: Unilateral cervical thymic cyst. J Laryngol Otol85: 293.1971. 37. Furuya S, Baba S: Cervical thymic cysts and parathyroid cysts. Keio J Med20: 103, 1971. 38. Shepard KA, Miller JD: Cervical thymic cyst. J Maine Mea’Assoc 64: 3, 1973. 39. Fahmy S: Cervical thymic cysts: their pathogenesis and relationship to branchial cysts. J Laryngol Otol86: 47, 1974. 40. Mikal S: Cervical thymic cyst. Arch Surg 109: 558, 1974. 41. Kherdekar MS, Kher MM, Sharma KD: Congenital thymic cyst of the neck. Indian J Med Sci 28( 10): 449, 1974. 42. Freifeld S, Petti G: Cervical thymic cyst. NY State J Med75( 14): 2553, 1975. 43. Hanid TK, Johnson AG, Kay L: Cervical thymic cyst. J Pediab surg 10: 141, 1975. 44. Johnson NJ, Bretlau P: Cervical thymic cysts. Acta Otol82: 143, 1976. 45. Sood VP, Chattopadhyay AK: Cervical thymic cyst. Eye Ear Nose Throat Monthly 55(3): 99, 1976. 46. Bailey LL, Hilde RL, Smith TR, Thompson RJ: Cervico-mediastinal thymic cyst with vocal cord paralysis. Cancer 39: 347, 1977. 47. Speer FD: Thymic cysts. NY Med Co/l Flower HOSPBull 1: 142, 1938.
The American
Journal Of Surgery
Embryologically, the thymus gland originates from the third branchial pouch bilaterally at the sixth week of development, as illustrated in Figure 1. During the subsequent three weeks these hollow pouches become cellular and descend into the mediastinum. Rests of thymic tissue commonly persist in the neck along the route of descent of the gland into the anterior mediastinum. Indeed, three varieties of thymic tissue located in the neck have been described in the literature. Among these, aberrant solid thymic rests are commonly found at autopsy and are usually of little clinical importance. Wenglowski [I] in 1912 demonstrated cervical thymic tissue in twenty-three of seventy-five patients at autopsy. Gilmour [2] in 1941 found thymic tissue in the neck of thirteen patients at autopsy. Such tissue may be confused with metastatic squamous cell carcinoma during frozen section examination at parathyroid exploration. The second type of thymic tissue encountered is cervical thymoma. These tumors have been found at both autopsy and operation for cervical mass [3-71. Finally, cystic thymic tissue is the most important of the three types of cervical thymus because of its clinical presentation. Cystic thymic tissue was first excised from a patient presenting with a neck mass in 1901 by Pollosson and Piery [8]. During the subsequent seventy-six years,
From the Division of Surgery*, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, DC, and the Uniformed Services University of the Health Sciences, Bethesda, Maryland. The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense. Reprint requests should be addressed to Alexander M. Guba, Jr, MD. Division of Surgery, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, DC 20012. Presented at the Joint Meeting of the American Society for Head and Neck Surgery and the Society of Head and Neck Surgeons, Toronto, Ontario, Canada, May 29-31, 1978.
430
fifty-five additional cases of cervical thymic cyst have been reported in thirty-nine publications [2,9-461. These fifty-six cases, with sixteen previously unreported cases of cervical thymic cyst, form the basis of the present report. Material and Methods Cases were obtained from the authors’ practices and the records of the Armed Forces Institute of Pathology (AFIP), Washington, DC. The patients’ records and pathology reports were reviewed, and hematoxylin and eosin preparations were examined by us. Results
Literature Review. Fifty-six cases have been presented in the literature with histologic confirmation of cervical thymic cyst. (Many of the references did not provide complete data concerning the patients presented. Percentages given are compiled from the available information.) The average age was twelve years, although the median age at presentation was seven years. Seventy per cent were male. Seventy per cent of the patients had left-sided neck masses, 23 per cent had right-sided neck masses, and the remainder had midline or pharyngeal masses. The cervical mass was noted to be present an average of 9.8 months prior to surgery, whereas the median time interval from onset to operation was three months. Ninety per cent of patients complained of painless swelling, 3 per cent noted a posttraumatic mass, and 6 per cent presented with dyspnea, hoarseness, and dysphagia. Present Study. Sixteen patients undergoing surgical exploration for a neck mass were found to have cervical thymic cysts. Two were treated at the Greater Baltimore Medical Center, one was treated at Walter Reed Army General Hospital, Washington,
The American
Journal of Surgery
Cervical
Presentation
of Thymic
Cysts
TONSIL HYPOBRANCHIAL
EMINENCE&
Ill-
INFERIOR
PARATHYROID
LARYNGOTRACHEALGROOVE
THYMUS
FOURTH
AND
FIFTH
RIOR
DUCT OF POUCHES YROID
Figure 1. Embryonic pouches.
remainder were asymptomatic. Six had right-sided neck masses, seven had left-sided masses, and three had midline neck masses. Ten of the sixteen masses were either within the anterior triangle of the neck or lying under the lateral border of the sternocleidomastoid muscle. Common preoperative diagnoses were branchial cleft cyst, cystic hygroma, lymph node, thyroid nodule, and thymus. Pathology. The principal gross and histologic findings are outlined in Table II. Intraoperatively, cervical thymic cysts were found to be variable in size,
Clinic&l Data Age WY
Case
GLAND
pharyngeal
DC, and two were treated at Fitzsimons Army Medical Center, Denver, Colorado. The charts and histologic sections of the tumors from the remaining patients were located at the Armed Forces Institute of Pathology, Washington, DC. Pertinent clinical data are shown in Table I. The average age of patients was 18.8 years. Seven males and nine females were included. The cervical mass had been present an average of 4.5 months prior to operation. Four patients had some degree of pain associated with the mass, one had dysphagia, and the TABLE I
PARATHYROID
Sex
Duration of Mass
Symptoms
1 2
7/M 25/F
5.5 mo 2mo
None Sore throat
3 4
15/M 14/M
1.5 mo 3 mo
Pain Dysphagia
5 6 7
36/F 35/F 26/M
3mo 4mo 16da
Tender 3 days Cough None
a
7/F
2 yr
None
9
30/F
Unknown
Thyrotoxicosis
10
4/M
Unknown
11 12 13
24/M 4/F 10/F
5 wk 5 da 7 mo
Pain None None
Right neck Medial border right sternocleidomastoid muscle Left neck Left anterior triangle Left neck Suprasternal notch Left anterior triangle Left anterior triangle Right suprasternal notch Right anterior triangle Left neck Right neck Right neck
14 15 16
22/F
3mo
None None None
Suprasternal notch Left neck Suprasternal notch
ah4 32/F
Volume 136, October 1976
1 yr 1 wk
Preoperative Diagnosis
Location
Branchial cleft cyst: cystic hygroma Branchial cleft cyst
Left neck mass Left neck cyst Branchial cleft cyst Unknown Unknown Cystic hygroma Toxic goiter Branchial cleft cyst Lymph node Thyroid nodule Branchial cleft cyst; cystic hygroma; thymus Anterior neck mass Cystic hygroma Thyroid cyst
431
Guba et al
TABLE II
Patholoaic Data Mediastinal Connection
Cyst Size (cm)
Case
I5 x 2.5 4X3X 1.5 4X 1.8 x 1.2 2x2 2.5 X 1.5 3X4X 2.5 7.5 x 4 x 3.5 5X4X 3.5
Contents of cyst Turbid gray-brown
CuboidaVsquamous
+
++
Turbid
+
+
Duct extending 12 cm inferiorly None Inferior fibrous tract None
Friable yellow-brown
Flattened cuboidab squamous Flat squamoid
++
+
Gelatinous Solid/cystic Serous
Stratified squamous Flattened cuboidat Low cuboidal
++ +
+ +
Cystic tail
Straw cofored
SquamousIcuboidal
+
++
Nipple-like projection 3 cm cystic None
Green-brown gelatinous
No lining
-
-
Unknown
None
Yellow fluid with hemorrhage Dry cheesy
Pseudostratified ciliated columnar Simple/stratified squamous Flat cuboidal
0.1 x 0.9
10
4.5 x 3 Xl 3.5 x 2.9 x 1.4 3x 1.5 x 1.5
None
None
Yellow-orange
14 x 3.5
Projection from mediastinum None Extension into mediastinum
Gray-white
Substernal pedicle
Unknown
12 13 14 15
1.5 15 x 4.5
16
1.5 x 2
Hassall’s Corpuscular Degeneration
Solid core into mediastinum None
9
11
Lining
Cholesterol Granuloma or Clefts
Unknown Unknown
soft, and usually lobulated. They were frequently elongated, possessing a cephalad or caudal extension, as shown in Figure 2. The wall of the major cyst space varied in thickness from a few millimeters to as much as 1 cm. Cyst contents varied from clear fluid to turbid, semi-solid material. Roth the external capsule and internal septae of the cysts were composed of highly cellular and vascularized fibrous tissue. Lymphocytes were present in aggregates and in a diffuse, scattered pattern, with both Hassall’s corpuscles and strands and nests of thymic epithelial elements found among them, as shown in Figures 3 and 4. Thymic cellular elements were in intimate relation to the cyst lining. Cholesterol type granulomata were present in eleven of sixteen patients. (Figure 5.) There was wide variation in the type of lining epithelium, as shown in Figure 6. Comments
From the clinical findings reported by others and from our own study involving sixteen patients, it can be seen that 75 per cent of patients with histologically
It
++
++
+
-
Flat cuboidal
++
-
Simple squamous
++
+
+
++
-
+
No lining Stratified squamous, flat granulation tissue Low cuboidal
proven cervical thymic cyst were less than twenty years old at presentation. Overall, cervical thymic cysts were found more frequently in males, even though a slight female predominance was noted in our study. More than 80 per cent of the patients complained of a slowly enlarging, painless mass. The remainder presented with dysphagia, hoarseness, and dyspnea. Occasionally, a cervical thymic cyst became suddenly evident or abruptly painful after an initially painless course, as in cases 3 and 5. Fluctuation in size, presumably due to infection or hemorrhage, was noted in cases 4 and 13. Symptoms were usually present for several months prior to consideration for operation. All cervical thymic cysts were said to be mobile at the time of physical examination. Concomitant diseases were present in two of our sixteen patients. One patient (case 11) initially presented with a left-sided tender mass that proved to be a cervical thymic cyst. Six months later, he presented with a second left-sided mass. This proved to be intranodal Hodgkin’s disease. Review of the sections of the initial specimen failed to show any diagnostic features of Hodgkin’s disease. Cervical
The American Journal of Surgery
Cervical Presentation of l’hymic Cysts
thymic cyst was a chance finding in a thirty year old female (case 9) operated on for thyrotoxicosis. The preoperative differential diagnoses included lymph node, branchial cleft cyst, cystic hygroma, and thyroglossal duct cyst. From the literature it seems that a firm diagnosis of cervical thymic cyst has not been made preoperatively. Case 13 from our series may represent a correct preoperative diagnosis. This ten year old female presented with a rapidly growing and very long lateral neck mass that proved to extend from the mandible to the mediastinum and measured 14 by 3.5 cm. A preoperative chest x-ray film revealed widening of the superior mediastinum and tracheal deviation to the left. It drew the written comment fl-om one clinician: “I think this is thymus.” It has been stated that as many as 50 per cent of cervical thymic cysts may be continuous with mediastinal thymus. This may be by direct extension of t:ne cyst substernally or by connection to a solid cord or vestigial remnant of thymic tissue which extends into the thorax. Such a connection was present in eight of our sixteen patients. Cervical thymic cyst has rarely required extensive operative time or dissection. F’rozen section diagnosis of cervical thymic cyst should help the surgeon determine the extent of the procedure necessary for removal of the tumor. Histologically, the presence of thymic epithelial elements in intimate relation to the cyst lining is essential to the diagnosis of cervical thymic cyst. Has~11’s corpuscles or diffuse thymic epithelial elements should be evident; otherwise the tissue cannot be histologically distinguished from tissue of a branchial cleft cyst. Cholesterol type granulomata or clefting is usually present. There is no uniformity regarding the composition of cyst lining in cervical thymic cyst. As in mediastinal thymic cysts, the lining may be nonexistent or it may be composed of cuboidal, ciliated columnar, simple squamous, or stratified squamous epithelium with variable amounts of inflammatory cellular infiltrate, granulomatous tissue, and fat-laden histiocytes. The origin of cervical thymic cyst has been debated in the literature. Speer [47] discussed five possible origins of cervical thymic cysts: (1) embryonic remnants; (2) sequestration of involuted areas; (3) degenerating Hassall’s corpuscles; (4) blood or lymph vessels; and (5) neoplastic processes. More recently, authors [27,44] have condensed these to two: (1) degeneration of Hassall’s corpuscles and (2) a congenital origin with tissue arising from the thymopharyngeal duct. All but five of our patients showed degeneration of Hassall’s corpuscles; the spectrum of degeneration extended from focal or partial degene:*ation of a corpuscle to the formation of a microcyst
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Figure 2. Case 4. Operative photograph of thymic cyst.
with a flattened epithelial lining identical to that of the main cyst cavity and surrounding granulomatous reaction. The granulomatous reaction to which we have already referred is consistent with a reaction to cholesterol and has repeatedly been described as such in the literature. To our knowledge, this has not been established histochemically. Moreover, although some authors suggest that it is caused by the breakdown products of hemorrhage, the evidence for intracyst bleeding (as hemosiderin pigment 1is scanty
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Figure 3. Case 4. Microcysts developing within thymfc cyst wall. Note cholesterol type cleftfng within the lumen. (Magnfffcatton X40; reduced 53 per cent. )
Figure 4. Case 15. Photomfcrograph of degenerating HassaIl’s corpuscle in cervical thymic cyst. Note development of epithelial lining similar to that of cyst cavity. (Magnification X lOti; reduced 53 per cent. )
in our series. We prefer to regard this as a foreign body reaction secondary to a product of epithelial cell degeneration, such as keratin. An observation favoring the congenital origin of cervical thymic cyst is the relatively frequent association of cervical thymic cyst with other endocrine gland inclusions. Five of our sixteen patients had fragments of other endocrine tissue. In cases 12 and
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15, discrete nests of normal parathyroid tissue were seen at a distance from the cyst lumen and were considered inclusions. Similarly, in case 7 a cyst in the left anterior cervical triangle had an inferior prolongation reaching into the superior mediastinum. Although the cyst was clearly of thymic origin, the tail contained normal thyroid tissue in close approximation to thymic elements.
The American Journal of Surgery
Cervical Presentation of lhymic
Figure 5. Case 3. cholesterol type mata in cervical nification X40; cent. )
Cysts
Photomicrograph of clefts and granufothymic cyst. (Magreduced 53 per
Figure 6. Case 15. Photomicrograph ikstrating variety of lining epithefium within a single specimen: simple cuboidal; flattened; and focally pseudostratified epithelium. ( Magnification X40; reduced 53 per cent. )
Two additicmal cases from AFIP files not included wit,h the sixteen reported herein were reviewed. It was not possible to be certain whether the appropriate diagnoses were parathyroid cyst with aberrant thymic tissue or vice versa. Considering the complicated descent of the thymic primordia and their common origin from the third branchial pouch with the parathyroid III glands, such close association
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between thymic and parathyroid tissue is not surprising. Thus, elements of both the congenital and degenerative theories have to be employed to adequately explain the development of cervical thymic cysts. Finally, it should be recognized that cervical thymic cyst belongs in the differential diagnostic list of neck masses, particularly in children and occasionally in adults.
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Summary
Sixteen cases of cervical thymic cyst are added to the previously reported fifty-six cases. Seventy-five per cent of the patients were less than twenty years old. Eighty per cent complained of a painless mass preoperatively. The histologic diagnosis of cervical thymic cyst was made if thymic epithelial elements could be found adjacent to the cyst cavity; Hassall’s corpuscles were usually present. Cholesterol granulomata could usually be identified. The theories of origin of cervical thymic cyst are discussed. Acknowledgments: We would like to acknowledge John White, MD, BG MC and Robert Muir, MD, COL MC for their contribution of two patients to this series.
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17. Sorensen HR, Jorgensen JB, Thomsen G, Westergard-Nielsen V, Eskelund V: Thymogenic tumours and cysts. Acta Chir Stand 110: 353, 1956. 18. Williams RR, Gerber DM: Aberrant cystic thymus gland of the neck. Am J Surg 93: 473, 1957. 19. Crawford AS, Evans PV, Thompson W: Thymic cyst in the neck; case report. J Indiana State MedAssoc 50(6): 715, 1957. 20. Willis RA: The Borderland of Embryology and Pathology. London, Butterworth, 1958, p 281. 21. Viar WN, Donald JM, Clemmons LH: Thymic cyst in the neck. Am Surg 25: 18, 1959. 22. Lane D: Thymic cyst. Med JAust 47: 419, 1960. 23. Cote R, For-tin C: Thymic cysts of the neck. Can J Surg 4: 566, 1961. 24. Ozlu C, Allen JD: Unilateral thymic cyst of the neck. J Ky Med Assoc 60: 743, 1962. 25. Lewis MR: Persistence of the thymus in the cervical area. J Pediatr61: 887, 1962. 26. Gaeckle DJ, Gerber ML: Thymic cyst in the neck. Am J Surg 103: 755, 1962. 27. Behring C, Bergman F: Thymic cyst of the neck. Acta Pathol Microbial Stand 59: 45, 1963. 28. Simons JN, Robinson DW, Masters FW: Cervical thymic cyst. Am J Surg 108: 578, 1964. 29. Keen JA: A case of persistent thymus diverticula in the neck. S Af[ J Lab C/in Med 10: 48, 1964. 30. Bieger RC, McAdams AJ: Thymic cysts. Arch fathol82: 535, 1966. 31. lndeglia RA, Shea MA, Grage TB: Congenital cysts of the thymus gland. Arch Surg 94: 149, 1967. 32. Ellis HA: Cervical thymic cysts. Br J Surg 54: 17, 1967. 33. Dabby V: Cervical thymic cyst. J F/a Med Assoc 56: 852, 1969. 34. Barrick B, O’Kell RT: Thymic cysts and remnant cervical thymus. J Pediatr Surg 4: 355. 1969. 35. Hinds EA. Linkner LM, Cloud DT, Trump DS: Ectopic thymic tissue of the neck. J Pediatr Surg 5: 460, 1970. 36. Ratnesar P: Unilateral cervical thymic cyst. J Laryngol Otol85: 293.1971. 37. Furuya S, Baba S: Cervical thymic cysts and parathyroid cysts. Keio J Med20: 103, 1971. 38. Shepard KA, Miller JD: Cervical thymic cyst. J Maine Mea’Assoc 64: 3, 1973. 39. Fahmy S: Cervical thymic cysts: their pathogenesis and relationship to branchial cysts. J Laryngol Otol86: 47, 1974. 40. Mikal S: Cervical thymic cyst. Arch Surg 109: 558, 1974. 41. Kherdekar MS, Kher MM, Sharma KD: Congenital thymic cyst of the neck. Indian J Med Sci 28( 10): 449, 1974. 42. Freifeld S, Petti G: Cervical thymic cyst. NY State J Med75( 14): 2553, 1975. 43. Hanid TK, Johnson AG, Kay L: Cervical thymic cyst. J Pediab surg 10: 141, 1975. 44. Johnson NJ, Bretlau P: Cervical thymic cysts. Acta Otol82: 143, 1976. 45. Sood VP, Chattopadhyay AK: Cervical thymic cyst. Eye Ear Nose Throat Monthly 55(3): 99, 1976. 46. Bailey LL, Hilde RL, Smith TR, Thompson RJ: Cervico-mediastinal thymic cyst with vocal cord paralysis. Cancer 39: 347, 1977. 47. Speer FD: Thymic cysts. NY Med Co/l Flower HOSPBull 1: 142, 1938.
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